Flame holder construction



June 21, 1960 F. w. BAILEY FLAME HOLDER CONSTRUCTION Filed Nov. 2, 1953 3 Sheets-Sheet 1 MIXTURE 0F GAIN IE I LOW PRE5SURE6O 4 zous- INVENTOR FRANK w. BAILEY ZmA [iwi ATTORNEY June 21, 1960 F, w. BAILEY FLAME! HOLDER CONSTRUCTION 3 Sheets-Sheet 2 Filed Nov. 2, 1.955

INVENTOR FRANK W. BAILEY BY A. @L

ATTORNEY June 21, 1960 F. w. BAILEY 2,941,362 FLAME HOLDER CONSTRUCTION Filed Nov. 2, 1953 3 Sheets-Sheet 3 INVENTOR FRANK \Al. BAILEY ATTORNEY FLAME HOLDER CONSTRUCTION Frank W. Bailey, Mountain View, N.J., assignor to Curtiss-Wright Corporation, a corporation of Delaware Filed Nov. 2, 1953, Ser. No. 389,768

16 Claims. (Cl. 60--39.72)

This invention relates to combustion apparatus and is particularly directed to combustion flame holder apparatus for jet engines.

The invention has been designed for use with jet engines inwhich maintenance of stable and eflicient combustion is diflicult particularly becauseof the high velocity of flow through the combustion chamber. In the case of combustion chambers having a high velocity gas flow, the flame holder apparatus generally comprises some form of blufl object disposed across the flow path of the combustible gases for stabilizing the flame in the wake of the flame holder. It is generally believed that the flame is stabilized in the wake of such a flame holder because of the eddying of the burning or hot gases in this region with these gases recirculating back to the flame holder where they function as a continuous source of ignition to the unburned combustible gases flowing past the flame holder. The flame stability of such a bluff object flame holder is increased by increasing its lateral dimensions, that is, by increasing its dimensions across the flow path of the combustile mixture. Any increase of the lateral dimensions of the flame holder is objectionable, however, because the extent to which the flame holder blocks the gas flow is then increased thereby increasing the pressure drop across the flame holder.

An object of the present invention comprises the provision of novel and simple flame holder apparatus capable of providing stable and eflicient combustion in high velocity gas streams with minimum blockage of the flow. A still further object of the invention comprises the provision of flame holder apparatus which takes advantage of the pressure gradient between the wake of the flame holder and a minimum pressure region on the surface of the flame holder to help induce recirculation of the hot or burning gases back to the flame holder.

For various reasons jet engines generally burn fuels which are liquid instead of gaseous at normal or room temperatures. In liquid fuel systems the fuel is generally sprayed into the air stream upstream of the flame holder apparatus so that liquid fuel impinges on said apparatus. It has been found that in such liquid fuel systems the flame is stable only so long as there is an accumulation of liquid fuel on the surface of the flame holder. If the flame holder surface becomes too hot any fuel on said surface immediately vaporizes ofl said surface and this apparently results in the concentration of fuel in the wake of the flame holder becoming insuflicient to support combustion. In the case of gaseous fuel systems, however, heating the flame holder surfaces has been found to greatly increase the flame stability. Accordingly a still further object of the present invention comprises the the outer surfaces of the flame holder which are heated by said recirculating gases.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Fig. 1 is a schematic view of a jet engine embodying the invention;

Fig. 2 is an enlarged view of the combustion apparatus of Fig. 1;

i Fig. 3 is a view taken along line 33 of Figs. 1 and 2;

Fig. 4 is a further enlarged view of one of the tubular flame holder units of Figs. l-3 and illustrating the adjacent flow conditions;

Figs. 5, 6, 7 and 8 are views illustrating modified forms of the tubular flame holder units of Figs. 1-4;

Fig. 9 is a view of a further modified form of flame holder unit;

Figs. 10 and 11 are sectional views 10-10 and 11-11 of Fig. 9;

Fig. 12 is a view of a further modification in which the flame holder unit is channel shaped instead of tubular;

Figs. 13 and 14 are views taken along lines 13"13 and 14-14 of Fig. 12;

Fig. 15 is a view of a still further modification in which the flame holder unit is annular; and

Fig. 16 is a sectional view taken along line 16-46 of Fig. 15.

Referring first to Fig. 1 of the drawing there is illustrated a ram-jet engine 10 comprising a duct-like member 12 having a center body 14 supported therein by struts 16 adjacent the forward end of the engine. The engine has an annular air inlet passage 18 and a combustion chamtaken along lines .ber 20 to which air is supplied from said inlet passage 18 provision of flame holder apparatus for a liquid fuel 1 system in which the fuel is discharged within the appa ratus and is at least partly gasified therein by hot gases recirculating therein from the wake of the flame holder apparatus and said gasified fuel is carried out of the flame holder apparatus by said recirculating gases for flow over and to which fuel is supplied by combustion flame holder apparatus 22. From the combustion chamber the gases discharge rearwardly from the duct member 12 through a nozzle 21 into the surrounding atmosphere to provide the engine with forward propulsive thrust.

Except for details of the structure of the combustion flame holder apparatus 22, as hereinafter described, the structure of the ram-jet engine 10 as described is conventional. As will become apparent, however, the combustion flame holder apparatus of the present invention is not limited to ram-jet engine use. Instead, said apparatus is of general use for stabilizing combustion in high velocity gas streams. For example, the combustion app-aratus of the invention could be used in a turbo-jet engine, either as the main combustion apparatus and/or as the afterburner combustion apparatus.

As best seen in Figs. 2 and 3, the combustion flame holder apparatus 22 comprises a plurality of flame stabilizing tubes 30 interconnected by flame cross-over tubes or channels 32. Each flame stabilizing tube 30 hasa closed, conical upstream part 34 and a cylindrical downstream part 36. As herein used upstream and downstream refer to the general direction of the air and other gas flow through the combustion chamber 29 over the outside of the flame stabilizing tubes 30.

The conical upstream part 34 of each flame stabilizing tube 30 has its apex directed in an upstream direction so that its walls diverge in a downstream direction. The cylindrical part 36 of each flame stabilizing tube 30 has its cylindrical wall and axis extending substantially parallel to the general direction of the adjacent fluid flow outside said wall through the combustion chamber 20. In addition the cylindrical part 36 of each flame stabilizing tube '30 has an inturned annular flange 38 at its downstream end providing the tube chamber '40 with a restricted opening d2 at its downstream end. As illustrated the annular flange 38 is inclined so that it is conical and extends in an upstream direction as well as inwardly. The upstream end of each cylindrical part '36 also has an inturned annular flange 44 which is inclined in generally the same direction as the flange 38 such that the surface of the flange 44 is conical and is substantially parallel to and spaced from the adjacent conical surface portion'of the upstream part 34 to form an annular passage therebetween. Preferably one or more annular rings 46 are supported between the flange '44 and the adjacent end of the upstream conical part 34, to divide said annular passage into a plurality of side-by-side annular passages 48, said rings having a conical shape so that their surfaces are substantially parallel to the flange 44 and to the conical part 34. Because of the conical slope of the upstream tube closure part 34 and of the rings '46 and flange 44, the annular passages 48 have their outer or discharge ends directed in a downstream direction relative to the adjacent flow over their flame stabilizing tube 30. l i

Fuel is supplied to the flame stabilizing tubes 30 from an annular fuel manifold St) from which fuel conduits 7 52 extend co-axially into the flame stabilizing tubes 30. Each fuel conduit 52 terminates within its flame stabiliz- 'ing tube chamber 40 at a point between the annular passages 48 and the open end 42 of said tube. The end of each fuel conduit 52 is closed but said tube has a plurality of side openings 54 adjacent said end for spraying fuel laterally therefrom into the chamber 40 of its tube 3( At least one of the flame stabilizing tubes 30 also has an igniter 56 which as illustrated may be a conventional spark plug type igniter. i. The flame stabilizing tubes 30 may be supported within the combustion chamber by the fuel conduits 52 or, for example, suitable struts (not shown) may be provided to support said tubes from the wall of said combustion chamber. It is not essential that all the fuel burned within the combustion chamber 20 be introduced within the tubes 30. For example, at least some of the fuel burned in the combustion chamber 20 could be introduced into the air stream upstream of the flame stabilizing tubes 30 in which case the fluid approaching and flowing over the upstream ends 34 of the flame tubes 30 would-comprise a mixture of fuel and air instead of just air. Thus it is also within Jthescope of the invention to introduce allthe fuel into the airstream upstream of the flame tubes 30. Preferably, however, at least some of thefuel is introduced into each flame tube 30 because, as hereinafter described, the burning or hot gases recirculating back through said tube helps to vaporize the fuel introduced in said tube. The manner in which the flame tubes 30 function to stabilize combustion .is diagrammatically illustrated in .Fig. 4 in connection with one of said tubes. When air il'ows over a tube 30 the velocity of the air adjacent thereto increases from the upstream end or apex of the tube :to an annular zone 60 adjacent to the junction of its "conical upstreampart 3'4 and its cylindrical part 36 thereby creating a relatively low static pressure condition in .said zone 60 adjacent to and about the outer ends of the annular passage 48. In addition a high pressure zone 62 of eddying and circulating air is created in the wake of the flame tube 30 whereby a static pressure differential exits between the zones 62 and 60 which induces recirculation of air back through the open end 42 of the tube 30 into the tube chamber 40 and out through the annular passages 48. Upon discharge of fuel from the fuel conduit 52 this recirculating air carries the fuel with it with the result that upon ignition, by the igniter 56'or from a flame cross-over channel 32, the zone 62 in the wake. of the flame tube 30 becomes filled with burning gases,

as illustrated in Fig. 4. The static pressure differential between the zones 60 and 62 causes these burning gases to recirculate back through the tube 30 to gasify the fuel discharging from the tube 52 into the chamber 40 whereupon this gasified fuel is carried out through the passages 48 to be ignited in the zone 62 by the eddying burning gasesv in. this zone. This recirculation is helped by the educer action of the air flowing over the downstream directed outer ends of the annular passages 48. Thus the passages 48 may be termed educer passages. The burning gases recirculating back through the tube 30 also heat up the cylindrical wall 36 of said tube thereby further increasing the flame stability. Initially the igniter 56 serves to ignite some fuel within its flame tube 30. However, after combustion has been established little or no burning may take place within a flame tube 30 of the fuel discharging from its fuel conduit 52, most of the burning taking place downstream of the tubes 30.

The annular-flange 38 at theopen end of each tube 30 helps to prevent the fuel discharged into a tube chamber 40 as well as other fluid within said chamber from flowing out through the open end 42 of said tube along its wall 36 and interfering with the aforedescribed recirculation of the burning gases back through said tube from the high pressure zone 62 in the wake of said tube.

In addition, as illustrated, the flange 38 induces eddying of the gases Within the tube chamber 40 thereby increasing the heat transfer to the wall 36 of said tube from the hot gases recirculating back through said tube. For these 'ing gases back through the tube opening 42 into the tube chamber 40 depends on the size of said opening and the temperature of the wall 36 of said chamber depends on the amount of gases so recirculating, the size of the opening 42 may have to be further limited to prevent the temperature of the wall 36 from becoming excessive.

The Wall 36 of a tube 30 is cooled both by the fuel discharged into its chamber 40 and by the fluid flow over -the-outside of said wall, the heat transfer from said wall to said fluid increasing with increase in the length of said wall and with decrease in the temperature of the fluid. It is clear therefore if the flame stabilizer tube 30 is used "in an environment where the temperature of the fluid flow thereover is quite high (as in the case of a turbo-jet afterburner), if only a small percentage of the fuel burned is discharged into said tube, and/or if the tube 'is relatively short, that the permissible size of the tube opening 42 may be limited by the maximum allowable temperature of its wall 36.

From what has been said it is apparent that the size of the opening 42 of a tube 30 is restricted by its flange 38 to induce eddying within the tube chamber 40, to prevent fuel and gases from flowing out through the open end of the tube and possibly to prevent the temperature of the tube wall 36 from becoming excessive. Preferably -the tube opening 42 is made as large as permitted by these limitations in order that the recirculation of hot and/or burning gases back through said tube opening into the tube chamber 40 is a maximum.

' The invention is not limited to the specific size, number and lateral spacing of the flame stabilizing tubes 30 illustrated in the drawing. For example, a smaller number of larger flame stabilizing tubes could be substituted and the use of but a single such tube in a combustion chamber is within the scope of the invention. A large number of small tubes 30 is, however, preferred to a smaller number of larger tubes because, in general, with the smaller tubes a given degree of flame stability can be obtained with less flow blockage. For ram-jet engine use the preferred physical shape of the tube 30 is one in which its cylindrical wall 36 has a length of four inches I ass-has s? along saidfltube with changes in the rate. of air flow overthe flame tubes 30. Hence itis desirable that-each tube 30 have a plurality of annular educer passages 48, as illustrated in Figs. 1-4, in order that'at least one of said passages has its discharge or outer end at said minimum pressure zone. Actually, however, one such annular passage 48 may be satisfactory. in whichcase the'rings 46-would be eliminatedanda single educer passage would be formed between and by the'flange'44- andthe adjacent portion of the conicalipart 34. Such a modification is illustratedin Fig.- 5 For ease of understanding, the parts .of-Fig. 5 havebeen. designated by the same reference numerals as the corresponding partsof- Figs. 1-4 but with a subscripta added'thereto.

The flame stabilizing; tube 30a of Fig. 5 islike the stabilizing tube 30- of :Figs. 1-4 except the-tube 30a has; but-one educer passage instead of a plurality of such passages. Hence no further description of Fig. 5 ap pears tobe necessary I The shapeof each flame stablizing tube is-n ot' limited to that illustrated in Figs. 1-5. For example, the upstream endclosure part, instead ofbeing conical, may have a more streamlined shape. In addition, the annular flange-forming a wall ofthe educer-passage'could likewise have a curved-cross-section. Such a modification is :illustratedin Fig. 6. The parts of Fig. 6 have been designated by the same reference numerals as the corresponding parts of Figs. 1-4 but with a subscript b added thereto. The operation of the flame stabilizingtube 30b is obviously similar to that of the flame stabilizing-tubes of: Figs. 1-5. The-curvature of-the'upstream end 341) ofthetubeSilb may result in a largermaximumflow velocity over thetube thereby reducing-the pressure in the minim-urn pressure zone 6%.

A still fuither reduction in-this pressure may be possible-by providing a lipon the flangeforming a wall of theeducerpassagea Such anarrangement is illustrated inFigz- 7. The parts ofFig. 7 have been designated by thesamereferencenurnerals as'the corresponding parts of Figs. 1-4 but with a subscript 0 added thereto. In Fig.7 the flange Me is provided with an annular-lip 70 projecting slightly out into theairstream over the tube 36C. Also in Fig. 7 thefuel' conduit is provided with a plurality of fueltubes 72extending. radially therefrom into the tube chamber 41%. discharge-opening at its radially. outer end and also has a plurality of fuel discharge openingsonitsside facing the annular educer passage toto aid-fuel flow towardsaid passage. Except for-thediiferences noted the-structureand: operation of the flame-stabilizer-tube 3iic'is like theflarne stabilizer tubes 39. 7

Most of the fuelsuppliedtothe chamber of each flame the flame stabilizer tubeof Fig. 7 most of the fuel is' dischargedinto the tube-charnber toward the educer passage of said tube. Pig. 8 illustrates a further modification having means for direetinglhe-fuel away from the openend of the-tube. In Fig. 8 the end of thefuel conduit is provided with a cap 74 for directing the fuel away from 'theopen end ofthe' fuel stabilizing tube and toward the educer passage of saidtube. In addition theflarne stabilizer tube of Figs-8- is provided with aplurality of circumferentially-spaced external fins 76 --to helpscool-its cylindrical-wall- Except for the addition of the cap 74- andfins 6, the flame'stabilizer tube of Fig. 8 is like that of the tube 313 of Figs; 1-4. Theparts of Fig. 8 have been designated-by. the same reference numerals as the corresponding parts of Figs. 1-4 but Each fuel tube 72 has-a fuel 1 with a subscript dadded thereto. The addition'of the cap 7 1 results in a decrease in the fu'elflo'wing' along the internal surface ofthe tube cylindrical wall 36a" whereby: the cooling effect of the fuel on said Well is decreased. Hence the addition oftlie fins76 at least partially compensates for said-decreased cooling effect of the fuel.

The most convenient arrangement for introducing the fuel into the-flame stabilizing tubes is probably, as illus trated in Figs. 1-8, from'a fuel conduit' disposed centrally; within the tube chamber. The central portion of the flame stabilizing tube chamber, however, has a relatively high temperature-and if said temperature becomes too high fuel will carbonize in the fuel conduit 52,.52a, 52b, 52kor 52d and/oririitsfuel discharge passages or-openings- In order to minimize any tendency of the fuel to socarbonize some air may be introduced through the fuel conduit along withthe fuel and/or the fuel con duit and its discharge openings-maybe "located along-the relative cool outer wallofthe flame stabilizing tube. This latter'arrangement is illustrated in Figs. 9-11 which is otherwise similar to Fig.5.

The parts of Figs. 9-11 have been designated by the same reference numerals as-the corresponding parts of Fig. Sexcept a subscript 2 has been usedin Figs. 9-11 instead of the subscript a of Fig. 5. In Figs. -9-ll thef flame stabilizing tube 3% is supported-at one end of ai' channel member 80 the other end of which is secured. to a wallof the combustion chamber (for example the chamber ZilofFig. 1) or to a strut extendingacross said cornbusti'onchamber for supportingthe flame stabili'zingr tube 3% within said'ch'amben- The fuel supply conduit 52a for the-flame stabilizing tube Stl'e extends" alongand within the channel member 84). The fuel c011" duit 52a terminates inanannular passage SZformed." about the flame stabilizing tube 3il-intennediate the" ends of its cylindrical part 366. In addition a plurality of short fuel discharge passages 84 are provided for discharging fuel from the annular passage 82'into the chamber the of the flame stabilizing tube 3%. Each of" the fuel passages 84 is inclined inwardly and toward the educer passage 482. Also, as illustrated in Fig. 11, eachof said passages 84 is tangentially inclined so that a swirlingmotion is imparted to the fuel as it'discharges into the flame stabilizing .tube chamber 4%. Small additional fuel discharge openings 86 may also be provided to insure some fuel cooling of-the flange 382 and the portion ofthe Wall 36a between the annular passage 82 and said flange and/ or fins (not illustrated). such as the fins 76 of Fig. 8 may be added about the wall 360 for helping to cool said wall. The flame stabilizing operation ofthe tube She of Figs. 9-11 is essentially the same as that of theflamestabilizing tubes of Figs. 1-8. The length of the fuel discharge passages 84 has been exaggerated inthe drawing in order to illustrate the ori entation of said passages.

In each of the -modifications of Figs. 5-11, the flame stabilizing apparatus preferably. comprises a plurality of the flame-stabilizing tubes interconnected by flame-cross over tubes or channel as in Figs. 1-3.

It is not essential that the flame stabilizing apparatus of the invention comprise one or more tubulan-units, such as 30, 30a, 30b, 36c, 30d or30e as inFigs. 1-11- For example each flame 'stabilizingunit instead of being. tubular could have the shape of a linear or annular channel. Figs. 12-14 illustrate a flame stabilizing apparatus in which each flame stabilizing unit has the shape of a linear channel. For convenience ofunderstanding: the parts of Figs. 12-14 have been designated by thesame reference numerals asthe correspondingparts of Figs. 1-4 but with a subscript f added thereto.

Figs. 12-14 illustrate flame stabilizing apparatus com-; prising one-or more flamestabilizing channel units 30?. disposed'in a combustionchamber 20f. Said apparatus may comprise a single unit 30foi a plurality 'of $1355 units in side-by-side relation. Each flame stabilizing unit 30] comprises a channel 34] and flat side wall extensions 361 of said channel part. The channel part 34 is of V-shaped cross-section and closes the upstream end of the unit 30). The side wall parts 36] extend downstream from the ends of the channel part 34 to form the side walls of a chamber 40;! within the flame stabilizer unit 30 said wall parts 36 being substantially parallel to the direction of the adjacent flow through the combustion chamber 20]. Each of the side Walls 36f has an inturned flange 38 at its downstream end forming a restricted opening 42f for one end of the chamber 40f, the other end of said chamber being closed by the part 34 As illustrated each flange 38) is inclined inwardly and toward the channel part 34 end of the chamber 40 In addition each of the side Walls 36 has aninturned flange 44] at its other end substantially parallel to and spaced from the channel part 34 to form an educer passage 48) therebetween. A fuel conduit 52f extends into the chamber 40 of the flame stabilizing unit 34 and a fuel tube 90 extends along said chamber laterally from the conduit 52 A plurality of fuel openings 54 are provided in the fuel tube for discharging fuel toward the side plates 36 A suitable igniter (not shown) may be provided for igniting the combustion mixture in a manner similar to that described in connection with Figs. 1-4.

The flame stabilizing operation of the unit 30] is substantially the same as that of the flame stabilizing tubes 30. Thus the fluid flow through the combustion chamber 20f over the flame stabilizing unit 34 produces a zone 601 of low static pressure along the outer or discharge end of each educer passage 48]. In addition the eddying of the gases in the wake of the unit 34 produces a relative high static pressure zone 62f so that recirculation of combustion gases is induced back into the chamber 40 of the unit 34 and out through the educer passage 48f.

Figs. -],6 illustrate a flame stabilizing unit which is substantially the same as that of Figs. l2l4 except instead of each channel unit being linear it is annular. Hence for ease of understanding the parts of Figs. 15-16 have been designated by the same reference numerals as the corresponding parts of Figs. 12-14 except a subscript g has been added. One or more such units 30g may be used in a single combustion chamber. A plurality of such units 30g of different radius can be used in a combustion chamber by mounting the units concentrically, the radii of the units being such that they can be concentrically mounted with an annular space therebetween. No further description of Figs. 15-16 appears to be necessary.

At this point it should be obvious that the distinctive features of the modification described could be combined like permutations and combinations. For example a plurality of side-by-side educer passages, as in the flame stabilizer tube 30 of Figs. 1-4, could be provided in each of the other flame stabilizer tubes 30a, 30b, 30c, 30d and 30e as well as in the flame stabilizer channel units 363 and 30g. Furthermore the end closure part of each of the other modifications could have a curved cross-section like the end closure part 341) of Fig. 6 instead of the V-shaped cross-section illustrated. Likewise fins, such as the fins 76 of Fig. 8, and/or the lip construction 70 of Fig. 7, obviously could be added to any of the other flame stabilizing tubes and to the flame stabilizing channel units of Figs. 12-16. Also either the fuel distributing means 72 of Fig. 7 or the fuel deflecting means 74 of Fig. 8 obviously could be added to the flame stabilizer tubes or channel units of the other modifications. In addition instead of introducing fuel from the center of the flame stabilizer tubes or channel units the fuel could be introduced from a. passage formed along a wall of said tube or unit as disclosed in the case of the flame tubes 30c of Figs. 9-11.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications. V

I claim as my invention:

1. In combination with a main combustion chamber having an entrance end through which air is supplied for combustion therein and having a discharge end through which gases discharge from said chamber; flame stabilizing means mounted within said chamber and comprising a wall structure forming an auxiliary chamber having a closed upstream end and an open downstream end relative to the direction of flow of main chamber gases over said stabilizing means, said wall structure comprising an upstream wall part diverging in a downstream direction relative to said flow and a side wall part extending substantially parallel to said flow and said wall structure having passage means therethrough intermediate the ends of said auxiliary chamber and directed outwardly from said auxiliary chamber in a generally downstream direction relative to said flow; and means for discharging fuel into said auxiliary chamber so that unburned fuel flows from said auxiliary chamber through said passage means for combustion with air supplied to said main chamber.

2. The combination recited in claim 1 in which said wall structure passage means is disposed between said diverging upstream wall part and said side wall part.

3. The combination recited in claim 1 in which said wall structure passage means extends substantially entirely about said auxiliary chamber and is disposed between said diverging upstream wall part and said side wall part.

4. The combination recited in claim 1 in which said wall structure passage means is disposed so as to open into the adjacent main chamber flow over said flame stabilizing means in a zone along said flame stabilizing means at which the static fluid pressure in said flow is relatively low.

5. The combination recited in claim 1 in which each end of said side wall structure part has an inturned flange inclined upstream relative to said main chamber flow, the flange at the downstream end of said side wall structure part forming a restricted downstream opening for said auxiliary chamber and the flange at the upstream end of said side wall structure part cooperating with the adjacent portion of said upstream wall structure part to form the walls of said passage means.

6. The combination recited in claim 1 in which said wall structure passage means is disposed so as to open into the adjacent main chamber flow over said flame stabilizing means in a region along said flame stabilizing means at which the static pressure in said flow is relatively low and in which the opening at the downstream end of the auxiliary chamber is restricted so that the cross-sectional area of said opening is less than the crosssectional area of said auxiliary chamber adjacent to said opening.

7. The combination recited in claim 1 in which said fuel discharge means comprises a plurality of fuel discharge openings disposed adjacent to and along said side wall part.

8. In a combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having 'a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprising a tubular member disposed substantially parallel to the direction of the adjacent fluid flow through said chamber and over said member; means providing an opening of reduced diameter at the downstream end of said tubular member relative to said flow; means disposed across the upstream end of said tubular fnember relative to said flow for closing said upstream end and for forming a substantially annular passage between-said end closure means and said tubular member, said last mentioned means progressively increasing in diameter toward said tubular member so that said annular passage is directed in a substantially downstream direction relative to said flow. 7

9. In a combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprisinga tubular structure disposed substantially parallel to the direction of the adjacent fluid flow throughsaid chamber and having a closed upstream end, an open downstream end of reduced crosssectional area relative to the cross-sectional area of the adjacent interior of said tubular structure and a substantially annular passage extending through the side wall of said tubular structure with the outer end of said passage being directed in a substantially downstream direction relative to the adjacent fluid flow over said tubular structure to therby promote flow through said passage by educer action; and means for discharging fuel into said tubular structure so that unburned fuel flows from the interior of said tubular structure through said annular passage for combustion within said chamber.

10. The combination with a combustion chamber of combustion apparatus mounted within said chamber; said apparatus comprising a tubular structure disposed substantially parallel to the direction of the adjacent fluid flow through said chamber and having a closed upstream end, an open downstream end of reduced cross-sectional area relative to the cross-sectional area of the adjacent interior of said tubular structure and a substantially annular passage extending through the side wall of said tubular structure with the outer end of said passage being directed in a substantially downstream direction relative to the adjacent fluid flow over said tubular structure; and means for discharging fuel into said tubular structure primarily in a direction other than toward the open downstream end of said structure for combustion within said chamber.

11. In a combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprising a tubular structure disposed substantially parallel to the direction of the adjacent fluid flow through said chamber and having an open downstream end of reduced cross-sectional area relative to the cross-sectional area of the adjacent interior of said tubular structure and having a wall closing the upstream end of said tubular structure and also having a substantially annular passage extending through the side wall of said tubular structure with the outer end of said passage being directed in a substantially downstream direction relative to the adjacent fluid flow over said tubular structure, said wall having an apex on the axis of said tubular structure and diverging in a downstream direction relative to said flow from said apex and said annular passage being disposed adjacent to the downstream end of said wall; and means for discharging fuel into said tubular structure so that unburned fuel flows from the interior of said tubular structure through said annular passage for combustion within said chamber.

12. In a combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprising a hollow cylindrical member disposed substantially parallel to the direction of the adjacent fluid flow through said chamber, said member actress l0 a images. inturned annular flange at. each end with each saidflange.v being inclined to the axis of said member in an upstream direction relative to said flow and with the flange at. the. downstream end of said member forming anopening. of reduced diameter compared. to the internal diameter of said cylindrical. member; a circular member: closingthe upstream end. of said cylindrical. member relative to the. direction of said combustion. chamber flow, said',circular member having an apex on. the axis of. said cylindrical member and diverging in a downstream direction relative to said flow from said apex with the downstream. end of said circular member being spaced from. the upstream end of said cylindrical member to form an annular passage between said circular member and the flange at the upstream end of said cylindrical member; and means for discharging fuel into said hollow cylindrical member so that unburned fuel flows from the interior of said tubular structure through said annular passage for combustion in said chamber.

13. The combination recited in claim 12 in which the diameter of the open end of said cylindrical member is no more than of the internal diameter of said cylindrical member.

14. The combination recited in claim 12 in which said fuel discharge means comprises an annular passage c0- axially formed in the wall of said cylindrical member with fuel discharge openings spaced therealong.

15. In a combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprising a plurality of tubular structures spaced laterally across the fluid flow through said chamber with each tubular structure disposed substantially parallel to the direction of said fluid flow; each said tubular structure comprising a hollow cylindrical member disposed parallel to said flow direction and having an inturned annular flnage at each end with each said flange being inclined to the axis of said member in an upstream direction relative to said flow and with the flange at the downstream end of said member forming an opening of reduced diameter compared to the internal diameter of said cylindrical member, and a circular member closing the upstream end of said cylindrical member relative to the direction of said combustion chamber flow, said circular member having an apex on the axis of said cylindrical member and diverging in a downstream direction relative to said flow from said apex with the downstream end of said circular member being spaced from the upstream and of said cylindrical member to form an annular passage between said circular member and the flange at the upstream end of said cylindrical member; and means for discharging fuel into the hollow cylindrical member of each of said tubular structures so that unburned fuel flows from the interior of each said tubular structure through its side wall annular passage for combustion in said chamber.

16. In a main combustion chamber having an entrance opening through which air is supplied for combustion within said chamber and having a discharge opening for the products of combustion; the combination therewith of combustion apparatus mounted within said chamber; said apparatus comprising a tubular member disposed substantially parallel to the direction of the adjacent fluid flow through said main chamber and having an end upstream wall and a side wall forming an auxiliary chamber therein with an open downstream end and with said end wall closing its upstream end, said tubular member also having means forming a passage through its auxiliary chamber side wall with the outer end of said passage being disposed and opening into the main chamber in a substantially downstream direction relative to the main chamber flow so that the fluid flow through said main chamber over said tubular member produces a pressure 1 1 differential in said main chamber between that atrthe open downstream end of said auxiliary chamber and that at said side wall passage by educer action so that fluid recirculates back into said auriliary chamber through its open downstream end and out through its said side wall passage; means positioned downstream from said passage for discharging fuel into said auxiliary chamber so that said recirculation carries unburned fuel out through said auxiliary chamber side wall passage for combustion in said main chamber immediately downstream of said tubu-' lar member whereby said recirculating fluid includes hot eornbustion gases; the open downstream end of said auxil iary. chamber having a reduced cross-sectionalarea compared to that of the adjacent interior of said auxiliary eha mber, saidupstream end wall having. an apex on the la 12,780,062

wall passage'is substantially annular.

. ReferencesCited in the file of this patent UNITED STATES PATENTS 2,517,015 Mock et al Aug. 1, 1950 2,554,401 Christensen et al May 22, 1951 2,592,385 Borden et al. Apr. 8, 1952 12,639,581 Cohen et al. May 26, 1953 2,659,199 Thompson Nov. 17, 1953 2,734,560 Harris et al. Feb. 14, 1956 

